http://diylilcnc.org/forum/topic/work-holding Free, open-source plans for a low-cost 3-axis CNC mill by Taylor Hokanson and Chris Reilly. Sponsored by the School of the Art Institute of Chicago. en-US Wed, 08 Sep 2010 13:32:09 +0000 http://bbpress.org/?v=1.0.2 q http://diylilcnc.org/forum/search.php http://diylilcnc.org/forum/topic/work-holding#post-378 Thu, 04 Mar 2010 20:55:31 +0000 DIYengineer 378@http://diylilcnc.org/forum/ <p>Very true bill, that would make for an easy quick exchange too, once the damaged Masonite gets ugly, just swap a new sheet in for cheap! </p> http://diylilcnc.org/forum/topic/work-holding#post-377 Thu, 04 Mar 2010 16:14:05 +0000 Bill 377@http://diylilcnc.org/forum/ <p>Covering the base with metal would concern me. If you mistakenly cut a little too deep, you could end up damaging the cutting tool or the Dremel. My plan is to cover the the 1/2" MDF base with 1/8" masonite or MDF, using screws in the corners and along the edges. If it gets damaged, it's cheap and easy to replace. </p> http://diylilcnc.org/forum/topic/work-holding#post-376 Thu, 04 Mar 2010 15:34:33 +0000 Chris 376@http://diylilcnc.org/forum/ <p>@MrPaul, for work-holding we've been using either double-sided tape or just screwing the material to the base with good results, though something like what you're describing may be more convenient. </p> <p>The interlocking base supports aren't necessary; we were mostly concerned with keeping the MDF bed from bowing over time, and the braces help to keep it level. Another easy work-around if you can't do dado cuts is to just have single spans in one direction to support the cutting base. </p> http://diylilcnc.org/forum/topic/work-holding#post-375 Thu, 04 Mar 2010 09:15:26 +0000 DIYengineer 375@http://diylilcnc.org/forum/ <p>Another modification is to pick up some 90 degree aluminum angle in 4 foot lengths, plexiglass, hinges, and pop rivets and make a box minus the bottom that slides over the whole machine with a door to load the materials in the front. This should keep your garage extra clean, i assume you could even run it indoors without a mess! </p> http://diylilcnc.org/forum/topic/work-holding#post-374 Thu, 04 Mar 2010 09:09:57 +0000 DIYengineer 374@http://diylilcnc.org/forum/ <p>Stacking them all together sounds like the way to go. Cant get more solid then 2.5" of pure MDF, PLUS it is QUICK! I would use wood glue in between and wood screws to screw each one to another. I would suggest 4 leveling rubber feet so it wont carry vibration and you can level the unit assuming what its going to sit on isn't always perfectly level. When it comes to being able to bolt or clamp a part to the table you can either strap the part which would be easy, but part may possibly move around, or while assembling the layers of the table together (assuming your using 1/2" mdf you will need 5 panels to reach the 2.5" thickness) Cut a matrix pattern of say 3"x3" using a 1" hole saw on the first 4 panels and on the last panel use a 1/4" bit to cut the same 3"x3" matrix pattern. Now you have a solid table, but still access to the underside of the table hold down pattern. You could then use 1/4" hardware to bolt the "to be milled part" to the table.</p> <p>I wonder if my 5.5hp sears shopvac could double as a vacuum hold down? It's pretty beastly and a simple matrix table top pattern and some simple plumbing could make a sweet modification. Just cover up the holes that would be in use with precut foam/wood/paper/metal to give maximum suckage to the part being milled. The table is so small just might work.</p> <p>My main concern ultimately was to sheath the mdf top to protect it from wear and tear. I also was planning on using a small air blaster hooked up to my compressor to blow out chips. Sometimes i get a small amount of blow by mist that the water trap didn't get, which would cause the mdf to warp and come apart. </p> http://diylilcnc.org/forum/topic/work-holding#post-373 Thu, 04 Mar 2010 04:49:32 +0000 Bill 373@http://diylilcnc.org/forum/ <p>I did the interlocking design. First, I clamped together all of the X spanning braces and then cut the slots on a table saw. I just treated the blade as a thin kerf dado blade and made 4 or 5 passes per slot. Once the X spanning braces were done, I did the same for the Y spanning braces.</p> <p>I'm still working on my build, so I haven't yet dealt with the hold down. What I was thinking, was to drill a matrix of 3/4" holes in the base (missing the underlying cross braces, of course). Then I could use some workbench hold-down clamps, made to work in those holes. </p> http://diylilcnc.org/forum/topic/work-holding#post-370 Thu, 04 Mar 2010 03:31:24 +0000 DIYengineer 370@http://diylilcnc.org/forum/ <p>I'm sure the interlocking design works great for the base, but if you have a good set of secure horizontal pieces i bet you would be fine as well. As for the table top i was going to use 1/2 MDF with .063" aluminum epoxied to the top. Then drill a 3"x3" hole pattern throughout the entire top. Underneath the holes i was going to use a 1/4" strip of aluminum wood screwed to the bottom side of the tabletop then drill and tap each hole from the top previous hole. This would give you a 3"x3" thread pattern that you could make all kinds of different custom hold downs out of simple bolts and other pieces of metal, plastic or wood. Hopefully that spring boards your imagination haha! Let me know what you think, i could always draw it up as well and post a picture! </p> http://diylilcnc.org/forum/topic/work-holding#post-369 Thu, 04 Mar 2010 02:42:39 +0000 MrPaul 369@http://diylilcnc.org/forum/ <p>So I am just about ready to start cutting panels and getting the base made. While looking at the base structure I was wondering what people were doing for work holding. I am tempted to mount and aluminum top plate with T-Slots milled out and or multiple small aluminum plates stacked and offset so that I would just have to cut rectangles out of the aluminum and save having to take the time to do the milling. I don't want to screw up the wooden / MDF base by screwing work pieces into it. No pun intended. Does anyone else have any ideas? For the people who have successfully completed the build what do you use?</p> <p>On another topic, for the MDF base, have people been doing the interlocking design or just the single set of horizontal braces? If you are doing the interlocking design how are you cutting the slots? A dado blade or router perhaps? I was tempted to try and do it on an existing CNC router, bu then we run into the issues with squaring off the interior cuts, and or doing an initial pass with a larger end mill and a finishing pass with a very small diameter end mill. I have seen some end mills with a diameter of less than 1mm, which would leave very little MDF to sand out to square up the slots. I am a little worried about breaking multiple bits though and they are quite expensive. Due to where I build I can't really use dado blades, so I'm not sure how else this would be accomplished. Are the interlocking panels really necessary? What about forgoing them all together and just stacking and gluing multiple MDF panels (5 1/2 panels) to make the requisite 2.5in height? Any concerns there besides the weight? I also though about making the cross braces non interlocking, which would mean many small parts, and trying to square them, drill them a dowel them. It doesn't seem like the best idea. So what's your take? </p>